Rims

I have a set of Magnum 500’s with the beauty rings . They are 9x14 with a 5 in backspace. What is a logical good looking tire to fit these for the rear of my car and what would an appropriate tire size be for the 7” stock magnums on the front to match up with the rears

With a 14" rim you have only limited options. That’s a pro or a con depending on how you look at it.

The major brands are Cooper Cobras, BF Goodrich T/A and Milestar Street Steel. I am using the Milestar 225/70 14’s but on 4.5” front and 5" rear. These end up being 26” diameter

What year Cougar? My 68 rubs a little with 225s in the front. Not enough to bother me but later models may allow for more option. If you already have front tires then pick a rear that is more wide but achieves the same diameters. Many online calculators can help with this. Try Tirerack.com

Thankyou